Soapmaking process



Jan. 31, 1961 SALT W. A. KELLY HAL SOAPMAKING PROCESS Filed July 16,195'? INVENTORS. WILLIAM A. KELLY 8 HARRY D. HAMILTON BY EW/ ,3 M

then ATTORNEYS.

process technique.

United States Patent SOAPMAKINGHPROCESS William A. Kelly, Teaneck, andHarry D. Hamilton, Montvale, NJ., assignors toLever'BrothersCompany, NewYork, N.Y., a corporation of Maine FiledJuly 16, 1957, Ser. No. 672,2146 "Claims. (Cl. 252-368) EI-his invention :is concerned with a .novelprocess for the manufacture of transparent :soap and with the productsobtained by-that process ;which.also possess all the desirableproperties of the highestiqualitymilled soap.

Although ithas been appreciatedthat soaps ordinarily identified .asmilled soap have some small degreeof translucency, they have notransparency and are not consideredbythose skilled in the soaprart astransparent soaps. Soaps are known in the art, however, .as transparentsoaps, and some .have enjoyed .for many years .a limited commercialappeal. However, such soaps are expensive due to themethod .ofmakingthem, andthose so-calledtransparent soaps'which attemptedto use cheapermethods of production are no longer :foundtobe acceptable by presentcdaycommercial standards.

One method-used in the production of .themore-accept- .able type oftransparent ,soapis to prepare a soap base .of reduced moisture contentand .then dissolve this soap in alcohol,.removing the saline impuritiesby decantation. Alcohol is recovered from thesoap by distillation. Thesoap mass then is cooled :to solidify ,and mold. This method isexpensive, time consuming, and involvesthe use of ahigh cost solvent. Acheapermethod for manufacturing a transparent soap used the well .knowncold Tallow lowiin free acid, coconut oil androsin are saponified withcaustic soda-in the presence of alcohol or alcohol and glycerin or inthe presence of a sugar solution, and the soap mass recovered andmolded. Another method involves the semi-boiled process and includescrutching the initial oils and fats at approximately 140 F., saponifyingwith caustic, then adding lye, and stirring until the soap has reached adesired consistency. This is followed by adding sugar dissolved inwater, or alcohol and glycerin, or combinations thereof. Themass isagain crutched at about 160 F., and desired perfume and dyestuff added.The soap mass is molded by framing, then slabbed, cut and pressed. It iswell known that neither the cold process nor the semi-boiled processproduced soaps of high quality.

Prior art processes for the production of transparent soap are discussedby F. W. Wells in Soap and Chemical Specialties, volume XXXI, No. 6 andNo. 7, June and July, ;1955. As is mentioned in these'articles, atransparent soap should be sutficiently transparent to permit boldfacetype of about 14 point size to be read easily through a section athickness of a quarter inch. It is with reference to this standard thatthe term transparent is used in this application in describing theproducts of the novel process.

The primary advantage of the method of this invention is that it makespossible for the first time the economical production of a transparentsoap having excellent lathering properties, firmness and a smoothappearance and waxy feel. The transparent soap can be produced withoutwaste or time loss and with minimum cost. There is no solvent used whichmust be recovered. No additive remains in the final bar product such assugar, rosin, alcohol, and the like which detract from its desirabledoes not tend to form unsightly cracks, as is the case with many milledsoaps. If the soap of the present invention is maintained forconsiderable lengths of time in contact with water, as happensoccasionally when an incompletely dryrsoapdish is used, it may becomecloudy .as .tothat contacted portion, but the soap, upon removal fromsuch contact, willzreturn to its original firmness and transparency.Furthermore, and most surprisingly, bars vof soap made by the process ofthis invention have the very desirable and unique advantage that theymay be v.nsed .even though worn to wafer thinness. Waste is thereforeavoided.

Soaps may range from .opaqueness through a translucencyaintotruetransparency, depending upon the method of manufacture. Various methodshave been used .to evaluate the translucency, and more specifically thetransparency of soaps. .A method for accuratelyrneasur-.ingthispropertymf .a .bar .of soap is by the use of the followingapparatus developed for this purpose. A bar .of soap .is placed, in .acompletely darkened room, on .toptof .a cone section surroundingalightsource of variable yoltage. The cone section has a diameter of /1 inchat the top and 2 /2 inches at the base, which .surrounds .the faceof:the light; the top of the cone section is 9 /2 inches above the face ofthe lamp, and the lamp is. amicroscope lamp .witha -volt, 15-wattbulbhaving a blue ground-glass filter. The voltage across :the lamp bulbis adjusted until the light from the top of .thecone section shinesthrough a bar havinga thickness of 2.75 cm. .and forms a barelyperceptible circular outline. The voltage acrossthe bulb is used as ameasure .of .translucency, which is independent of color and is termedTranslucency Voltage or TV. Thus, the lower the TV is, the moretranslucent the bar. ,-It is possible to measure readily the TV at otherbar thicknesses and interpolate to the standard of 2.75 cm. used herein.This method of determiningtranslucency is believed .to be superior to areflectance test described :in the art, because it is relativelyunaffected by .soap color and .gloss and avoids the difficulty ofcutting a soap bar to ,arequired thickness-of only of an ,inch.

.Forpurposes of comparison, an ordinary milled toilet soap of good.quality, even in the absence of pigments such as titanium dioxide whichmake it opaque, has .a TV .01? greater than 110, -i.e., it is too opaqueto be measured ,on-the apparatus described. This is despite the'factthat .it has the sheen and glossiness which are commonly referred to asthe translucency of milled soap, to distinguish it from the ,dull natureof frame soaps. The products of the present invention, on the otherhand, have .a IV of 35 ,or less, generally 30 or less, when freshlymade. A bar of soap with a TV of 30 or less meets the standard requiredto be called transparent.

In general, with the soaps of this invention there is an improvement intransparency upon aging of about six days or more, and in particular itis possible topractice our invention and produce a soap which, whenfresh, may have .a TV of morethan 30, even as high as about 35, whichsoap, when aged, will acquire the transparent properties of a soap of aTV of about 30 or less. The difference betweena barof soap having a TVof25 and one having a TV-of 35 is quite obvious to the unaided eye.

The most convenient starting material for the present process is soapinitially containing from about 28% to about 34%.. usually approximately30% to 32%, moisture, e.g., a neat kettle soap. The precise compositionof the initial stock used to prepare the soap is not critical as long asthe composition does not differ materially from those ordinarilyemployed in the manufacture of milled toilet soaps. Thus, for example,the relative proportions of fatty acids from tallow and from coconutoil, and the relative effects of such ingredients on the physicalcharacteristics of milled toilet soap produced therelow soap to about25% coconut oil soap is particularly good.

When neat kettle soap, which is in the liquid state, is used as thestarting material, it is first subjected to ordinary crutching, duringwhich free fatty acids, for example those from coconut oil, are added inorder to reduce the free alkali to a very low level. This crutchingoperation is not a critical feature of the invention and may beconducted by any conventional crutching method. The mixture duringcrutching is, as is conventional, in the liquid phase, at a temperatureabove 180 F., and preferably above 205 F. The crutched kettle soap,which has a moisture content of from about 28% to 34%, usuallyapproximately 30% to 32%, is next subjected to a drying step. As will bedescribed below, the water level of the finished soap bar must be in arange within certain limits, and the drying is therefore carried out toan extent which permits this range to be readily ob tained. The dryingstep can be carried out by any of the conventional drying methods, forexample ordinary cabinet drying. It is, however, preferred to use themethd commonly known as flash drying or, most preferably,

the method of tubular drying as is described in U.S. Patent No.2,710,057 of Bassett and Packard. When either flash drying or tubulardrying has been used, the soap at the end of the operation will be inthe molten state. It is then chilled and solidified, preferably intoflakes, before the mixing. There are some advantages, although notcritical, in conducting the chilling operation rapidly. When ordinarycabinet drying is used, the soap will be in solid flaky form after thedrying.

The next operation is conveniently that of mixing the soap flakes.Mixing provides the opportunity to incorporate such optional ingredientsas perfume and coloring matter. It is also a convenient time to adjustthe water content, and the salt content. The condition of the soap massat the time of the mixing operation preferably should be one in which itwill permit a working and shearing of the mass to be performed. Forexample, the soap mass should not be so hot that it is too soft or fluidto resist the operation of the mixer. For this reason, the temperatureof the soap at the beginning of the mixing step should be below about 90F., and preferably should be in the range of from 80 to 85 F. During themixing of stocks of usual types and with usual mechanical equipment andtime, the temperature should not rise above about 110 F., and preferablynot above 106' F.

At some point, preferably before the end of the mixing step, themoisture content and the salt content must be adjusted so that in thefinished product they will be within the limits which will be discussedbelow. During the mixing step, small amounts of various optionalingredients are added when desired. These include such substances asperfume, coloring materials, lanolin, resin, sorbitol, andpreservatives. The presence or absence of any, some, or all of theseoptional ingredients is not controlling to the production of atransparent soap bar having the desired characteristics of a high grademilled soap.

Neat kettle soap is a convenient example of the soap stock used. It is,however, not necessary that this be the starting material. What isrequired is simply a soap mass, however prepared, which is capable ofhaving its moisture and salt contents adjusted to levels which permitthe finished soap bar to have moisture and salt levels within thecritical range to be discussed below. The drying of neat kettle soap isonly one of the possible ways of obtaining such a soap and watermixture. An alternative method is, for example, the reaction betweenfree fatty acids and alkali, to which reaction mixture water is added orremoved as required in order to obtain a moisture content within therequired range.

Particularly in the case of neat kettle soap which has been dried by thetubular or flash method and subsequently chilled rapidly, a satisfactorydegree of transparency is obtainable as early as during the mixing step.

To accomplish this, the amount of soap in the mixer and the type ofmixer blades employed must be such that the soap offers a high degree ofresistance to the motion of the blades; because of this resistance, themechanical energy of the mixer blades is converted into heat energy, andthe desired temperature of the mixture thereby obtained without additionof heat from an external source.

To obtain high degrees of transparency during the mixing, the mixing isconducted for periods of time of about a half hour, the temperaturethereby being raised to between to F., preferably to between 103 F. and106 F. Generally in commercial production it is not convenient to spendthis amount of time in mixing, since the desired transparency is moreconveniently obtained during the subsequent milling, which need be nomore than a nominal amount. The time of mixing generally employed istherefore about 15 minutes, although as little as about 4 minutes isenough to obtain satisfactory blending in of added materials such asperfume or dye. The amount of working required will vary somewhatdepending upon the particular soap stock and the particular workingdevice used. The mixing times mentioned above are those for aBarbour-Stockwell mixer with thick counter-rotating blades. It is,however, a matter of routine testing to find the preferred conditionswhen other types of working are used.

It should be understood, however, that it is not critical to the processof preparing a soap bar of satisfactory transparency that any particulartype of mixer be used, or that there be any mixing step at all. Rather,the type of mixer is of consequence only in those cases where it isdesired to obtain a high degree of transparency during the mixing stagerather than at a different stage. It should also be understood that inorder to obtain a high degree of transparency during the mixing, it isnecessary that the mechanical energy of the moving mixer blades be takenup by the soap in the form of heat energy. Thus, a high degree oftransparency will not be obtained during the mixing when a mixer withblades which pass through the soap without encountering much resistanceis used along with heat supplied externally.

It is detrimental to the obtention of transparency, not only during themixing but at any subsequent stage, to allow the temperature of the soapmass to be above about 110 F. during the mixing. Preferably thetemperature is kept below 106 F.

The working effect of mixing is preferably amplified by subjecting thesoap mass to milling. A single pass over two five-roll mills is normallysufficient. In order to obtain a satisfactory degree of transparency, itis critical that as the soap mass emerges from the mill it be at atemperature of from 100 F. to about 110 F., pref erably from 103 to 106F. Soap not already transparent becomes so during milling, provided ithas the correct salt and moisture content, and provided suitablecritical temperatures "havebeen maintained. It is to be understood thata refiner of the type described in Patent No. 2,005,333 may besubstituted for the usual mill rolls and mixer, assuming always that thesame suitable conditions are maintained relative to the soap stock used.Itis thus seen that what is required to make transparent soap by theprocess of the present invention is that a soap mass having the criticalsalt and water proportions be subjected to working, its temperatureraised to within the range of 100 110 F., preferably 103 -106 F., andsubsequently formed into bars. The working may take place during amixing ,and/or a milling operation.

One of the functions of the milling operation is that the soap emergesfrom the mill in the form of very thin, flaky layers suitable forcompacting by plodding into a bar form. The remaining steps in theconversion into bar form are not critical features, and are successfullyaccomplished by any conventional means. There is, however, an advantageto the use of vacuum plodding, since it most conveniently prevents airfrom becoming entrapped in the soap bar and thereby impedingtranslucency. It is advantageous that the soap leave the plodder at atemperature of from 98 to 110 F., preferably from 103 to 106 F. Afterthe plodding, the soap is cut into individual cakes by usual means.

As has been mentioned above, it is critical to the process of thisinvention that, at least before the end of the working, the water andsalt contents be adjusted so that the finished soap has a water and saltcontent within a critical range. During the milling and ploddingoperation, a certain portion of the water, usually an amount suificientto reduce its percentage in the mixture by about 2 to 3, may be lost byevaporation, and this loss must be borne in mind when the water contentis adjusted.

The interrelationship of the salt and water content of afreshly ploddedsoap utilizing a conventional soap stock involving approximately 75%fatty acids from tallow and 25% fatty acids from coconut oil isillustrated by Way of example in the attached drawing. This drawing ingeneral illustrates by area B the relationship of salt and water whichpermits the production of a transparent soap bar as freshly plodded.Area A, outside of area B, illustrates a relationship of salt and watercomposition which results in a transparent soap having a TV value of 30after a reasonable period of aging, such as six days. Such soaps lyingin area A would have a TV value as high as 35 when freshly plodded.

It is to be noted that area B shown in the attached drawing is notrectangular but generally oval and represents a range of soapcompositions having a water content of from about 17.8% to about 21.9%,and a salt content of from about 0.16% to about 0.65%. Area A lyingoutside of area B represents water content limits of about 17.6% andabout 22.6% and salt content limits of about 0.12% and about 0.72%.There may be instances in which a soap having a higher salt and highermoisture formulation lying in an area involving a higher moisture andsalt content outside of area A will acquire a TV value of 30 or lessafter aging for a period of a month or more. For example, a freshlyplodded soap bar of 25% Water and a salt content of 0.90% may ultimatelyacquire a TV value of 30 or less, assuming the other critical steps ofthe process have been carried out as described above. This particularphenomenon is apparently one of ultimate loss of water by a slow dryingout of the soap bar. This is similar to the previously describedphenomen that occurs when a bar is soaked in water and becomes cloudybut which after drying returns to the original transparency. Thisparticular area, however, is of no great importance commercially due tothe fact that aging may be required for a period as high as severalmonths in order to obtain a transparency having a TV value of 30 or lessin the soap bar. Also warped or shrunk bars may result due to loss ofmoisture.

With a soap having a water content above 25 however, milling andplodding are not eflectively performed because the soap is too fluidunless its salt content is very high, that is, above about 0.95%. Barsof sodium soap having a salt content above about 0.95%, however, never,even upon prolonged aging, develop transparency even when otherwise madein accordance with the process of this invention.

The areas in which the salt and water content should lie to obtain atransparent soap are shifted somewhat upward and to the left, i.e.,toward a range of higher salt content and lower moisture content, when aportion of the soap, say from 5% to 25%, is potassium soap instead ofsodium soap.

When in the specification and the claims the term salt is employed,particular reference is made to .sodium chloride, but it is alsointended to include other water-soluble, soap-compatible electrolytessuch as sodium carbonate, potassium chloride, sodium sulfate, sodiumsilicate and sodium tripolyphosphate. There is some evidence to indicatethat when the salt is sodium tripolyphosphate, transparent soap isobtained when the areas A and B in the attached figure are shiftedsomewhat to the left, i.e., toward somewhat lower moisture contents.

Throughout the entire specification and in the claims, all percentagesare percentages by weight.

The following examples are given solely for the purpose of illustrationand are not to "be deemed limitations of this invention, many variationsof which are possible without departing from the spirit or scopethereof.

Example I Kettle soap, the soap portion of which contained approximatelytallow sodium soap and 25 coconut oil sodium soap, the mixturecontaining about 0.25% sodium chloride and an alkalinity of 0.15%expressed as sodium oxide, was charged into a crutcher, and the freealkalinity reduced to between 0.025% and 0.04% by the addition ofcoconut fatty acid. During the crutching, which was at 205 F., themoisture content of the soap was adjusted to 30-32%.

By the tubular drying method of US. Patent No. 2,710,057, the moistureof the soap was reduced to between 19-20%. The soap was then chilledrapidly on a chill roll to -85 F. The dried chips were weighed into at900-1000 pound mixer fitted with thick counterrotating blades. 2% waterand suflicient sodium chloride to adjust the finished bar to 0.4% saltcontent were added. The batch was then mixed for 15 minutes. During thisperiod, the temperature of the soap rose from 80-85 F. to -105 F.Without the addition of external heat. During this same 15 minuteperiod, the soap was converted to a partially transparent state. As thebatch was being mixed, the moisture of the soap was determined, andadjusted to 22% water by the addition of water.

The mixed batch was then milled by a single pass over two five-rollmills. The clearances between the mills were 0.040, 0.025, 0.015 and0.010 inch in the first mill and 0.025, 0.015, 0.010 and 0.005 inch inthe second mill. The temperature was controlled so that the soap leftthe second mill at a temperature between 100 and 106 F. At the end ofthe milling, the soap was highly transparent. The soap was then ploddedinto a continuous bar using a vacuum plodder, the extrusion temperaturebeing 103 106 F. The moisture content of the finished bar was 19.5%, andit had a TV of 28. As freshly prepared, bars of soap made by thisprocedure consistently had a TV no greater than 30, generally between 26and 28, and after about 6 days aging, a TV of between about 20 and 25,generally nearer 20.

Example 11 The procedure of Example I was followed, except that duringthe crutching, 0.1% of the sodium salt of ethylene diamine-tetraceticacid was added as a preservative, and during the mixing the followingingredients were added: 0.7% fern cologne-type perfume, 1.0% lanolin,and 0.0016% Monastral Fast Green pigment. The TV of the finished productwas the same as the product in Example I.

Example III The procedure of Example II was followed, except thatbesides the ingredients added in Example 11, 1.0% Staybelite resin and0.7% sorbitol were also added during the mixing. The TV of the soap madeby this method was slightly improved over that of Example I and ExampleII when the products were compared in the freshly made state, but whencompared after about a week of aging, they were substantially the same.

Example IV The procedure of Example I was repeated, except that themixing was continued for 30 minutes, instead of for only 15 minutes asin Example I. By the end of the 30 minutes of mixing, the temperature ofthe mixture was 106 F., and the soap was transparent. It was thenplodded in a vacuum plodder without milling, and the freshly made barshad a TV of 30 or less.

Example V Kettle soap, the soap portion of which contained approximately75% tallow sodium soap and 25% coconut oil sodium soap, the mixturecontaining about 0.25% sodium chloride and an alkalinity of 0.15%expressed as sodium oxide, was charged into a crutcher, and the freealkalinity reduced to between 0.025% and 0.04% by the addition ofcoconut fatty acid. During the crutching, which was at 205 F., themoisture content of the soap was adjusted to 30-32%.

By the tubular drying method of US. Patent No. 2,710,057, the moistureof the soap was reduced to between 19-20%. The soap was then chilledrapidly on a chill roll to 80-85 F. The dried chips were weighed into at900-1000 lb. mixer fitted with thick counter-rotating blades. 2% waterand sufficient sodium chloride to adjust the finished bar to 0.4% saltcontent were added. The batch was then mixed for 3 minutes, at the endof which time the temperature was still in the 80-85 F.

range.

The mixed batch was then milled by a single pass over the two five-rollmills previously described. During the milling, the mechanical energy ofthe rollers was converted into heat energy, and the temperature of themills was controlled so that the soap rose from the original 80-85 F. to103106 F. At the end of the milling, the soap was highly transparent. Itwas formed into bars by plodding.

Example VI The procedures of Examples I through V, inclusive, were allcarried out repeatedly, the only changes being in the water content andthe salt content of the finished soap bar. When the water and saltcontents were within the area A of the attached drawing, the freshlyprepared bars had a TV of 35 or less, and when the water and saltcontents were within the area B of the attached drawing, the freshlyprepared bars had a TV of 30 or less. Similar results were obtainedusing sodium carbonate, potassium chloride, sodium sulfate, and sodiumsilicate as the salt.

Example VII The procedure of Example I above was repeated, but the saltcontent of the finished bar was 0.9% and the moisture content was 24%.Bars of soap freshly made by this procedure had a TV of about 47, butafter aging for about 6 months, the TV was less than 30.

Example VIII To illustrate the criticality of the limits of water andsalt content, the procedures of Examples I through V, inclusive, wererepeated, but the water content of the finished bars was 20%, and thesodium chloride content was 1.0%. The bars all had TV values above 110,i.e., they were too high to measure by the method described. Althoughthey had luster, they were not truly translucent, but were actuallyopaque.

Example IX A soap was prepared and crutched as in Example I. It was thencabinet dried to a moisture content of 20.5%. The dried soap was thenmixed and milled as in Example I. The product was highly transparent.

Example X The procedure of Example I was repeated, except that the soapwas milled at 94 F. and extruded from the plodder at 93 F. As freshlymade, the soap bar had a moisture content of 19.7%, but its TV was 44.

Example XI The procedure of Example I was repeated, except that the soapwas milled at 120 F. The finished bar was opaque.

It is to be understood that various modifications of the method andproduct described herein will readily occur to those skilled in the art.All such modifications are intended to be included within the scope ofthe invention as defined in the accompanying claims.

This application is a continuation-in-part of copending applicationSerial No. 456,148, filed September 15, 1954, by William A. Kelly andHarry D. Hamilton and now abandoned.

What is claimed is:

1. A process for making a transparent soap bar having a translucencyvoltage of no greater than about 35, said process comprising workingbelow about 110 F. a toilet soap mass having a very low level of freealkali wherein the mechanical energy is converted into heat energy byworking to an extent great enough to cause the mixture to rise intemperature to within a range of from about 100 F. to about 110 F., themoisture and water-soluble, soap-compatible, alkali metal salt contenthaving been adjusted prior to the end of the working step to lie withinthe combined areas A" and B of the drawing hereof in the finished bar,and plodding the soap mass into bar form.

2. A process for making a transparent soap through which mass one-fourthinch thick, a 14-point boldface type is readable, said processcomprising working at a temperature above F. and below 110 F., a toiletsoap mass having a very low level of free alkali whereby heat isgenerated throughout said mass by such working, reducing said mass at atemperature between and 1l0 F. to a form suitable for plodding, ploddingsaid soap mass into a bar form, the moisture and watersoluble,soap'compatible, alkali metal salt content of said mass having beenadjusted prior to plodding to a range within combined areas A and B ofthe drawing hereof.

3. A process for making a transparent soap having a translucency voltageof less than 35, said value being based upon the voltage required totransmit sufficient light from a 15-watt, 120-volt microscope lampthrough a blue ground-glass filter at a distance of 9 /2 inches, topenetrate a 2.75 cm. thickness of said soap and form a circular outlinetherein, said process comprising reducing the moisture content of amolten neat kettle soap composition having a very low level of freealkali to substantially less than 22.6% moisture and a water-soluble,soap-compatible, alkali metal salt content to substantially less than0.72%, working said soap mass whereby the temperature rises to not morethan F., reducing the mass to a ploddable form, and plodding into barswhile maintaining the temperature substantially uniform, whereby a waxytextured, transparent, isotropic, microcrystalline soap is obtained.

4. A transparent soap bar prepared by the process of claim 1.

5. A process for making a transparent soap through which mass one-fourthinch thick, a 14-point boldface type is readable, said processcomprising working at a temperature above 90 F. and below 110 F., atoilet soap mass having a very low level of free alkali whereby heat isgenerated throughout said mass by such working, reducing said mass at atemperature between 100 and 110 F. to a form suitable for plodding,plodding said soap mass into a bar form, the moisture and watersoluble,soap-compatible, alkali metal salt content of said mass having beenadjusted prior to plodding to a range within area B of the drawinghereof.

6. A transparent soap bar prepared by the process of claim 5.

Compa Aug. 18, 1953 Ferguson Aug. 17, 1954

1. A PROCESS FOR MAKING A TRANSPARENT SOAP BAR HAVING A TRANSLUCENCYVOLTAGE OF NO GREATER THAN ABOUT 35, SAID PROCESS COMPRISING WORKINGBELOW ABOUT 110*F. A TOILET SOAP MASS HAVING A VERY LOW LEVEL OF FREEALKALI WHEREIN THE MECHANICAL ENERGY IS CONVERTED INTO HEAT ENERGY BYWORKING TO AN EXTENT GREAT ENOUGH TO CAUSE THE MIXTURE TO RISE INTEMPERATURE TO WITHIN A RANGE OF FROM ABOUT 100*F. TO ABOUT 110*F., THEMOISTURE AND WATER-SOLUBLE, SOAP-COMPATIBLE, ALKALI METAL SALT CONTENTHAVING BEEN ADJUSTED PRIOR TO THE END OF THE WORKING STEP TO LIE WITH-